QGraphicsView::setTransformationAnchor(AnchorUnderMouse) drifts when zooming with trackpad

When QGraphicsView is set to AnchorUnderMouse, zooming in and out with the trackpad causes the reference scene position (under the cursor) to drift. This issue does not occur when zooming in and out with the mouse wheel.
This effect seems to be even more pronounced on Mac OS and/or if inertial scrolling is enabled.

Steps to reproduce this issue:
1 - Open the "40000 Chips" qt example.
2 - Press and hold Ctrl to enable zoom while scrolling
3 - Scroll up and down many times using two fingers on the trackpad/touchpad and observe the scene position under the mouse.
4 - The scene drifts/pan sideways as we do that many times

Expected behaviour:
4 - Just like when using the mouse wheel, the position under the mouse should stay constant

May be related (but not the same) to https://bugreports.qt.io/browse/QTBUG-73033